Arrangement for interconnection of waveguide structures and a structure for a waveguide structure interconnecting arrangement

ABSTRACT

An arrangement (100) for interconnection of waveguide structures (10,20) or components comprising a number of waveguide flange adapter elements (100) having a surface of a conductive material with a periodic or quasi-periodic structure (15) formed by a number of protruding elements (115) arranged or designed to allow waves to pass across a gap between a surface around a waveguide opening (3) to another waveguide opening in a desired direction or waveguide paths, at least in an intended frequency band of operation, and to stop propagation of waves in the gap in other directions. Interconnection with a waveguide flange or another waveguide flange adapter element is allowed without requiring electrical or conductive contact and assuring that the gap is present between the at least one surface (15) formed by periodically or quasi-periodically arranged protruding elements (115) and a surface around a waveguide opening of the other waveguide flange (20), hence assuring that the surface (15) formed by the periodically or quasi-periodically arranged protruding elements (115) is not in direct mechanical contact with the other, opposite, interconnecting, waveguide flange (20).

FIELD OF THE INVENTION

The present invention relates to an arrangement for interconnection ofwaveguide structures. The invention relates to arrangements for use inthe high, or very high, frequency region, for example, above 30 GHz, oreven above 300 GHz, but also for frequencies below 30 GHz. The inventionalso relates to a structure for an arrangement for interconnectingwaveguide structures.

BACKGROUND OF THE INVENTION

For measuring and/or analyzing microwave or millimeter circuits anddevices of different kinds, for example, from filters, amplifiers etc.to much more complex multifunction systems, but also for other purposes,waveguide structures need to be interconnected, and normally so called“waveguide flanges” are used as transitions. The requirements for a goodconductive contact between waveguide flange surfaces are high. Unlessthe conductive contact is very good, currents will flow between theflanges, resulting in a leakage, mismatch and losses which will reducethe performance of the circuit, and produce incorrect results in thecase of measurements and calibrations, particularly at high frequencies.In order to assure a good conductive, electrical, contact, waveguideflanges need to be tightly and evenly connected to each other, forexample, a waveguide flange has to be tightly and evenly connected to adevice under test or to a calibration arrangement. In addition, anextremely good waveguide machining is required in order to assure a goodalignment between waveguide flanges. These are difficult andtime-consuming operations, in particular if several measurements need tobe done, and may lead to incorrectly attached systems.

In E. Pucci, P-S.Kildal, “Contactless Non-Leaking waveguide flangeRealized by Bed of Nails for millimeter wave Applications”, 6^(th)European Conference on Antennas and Propagation (EUCAP), pp. 3533-3536,Prague, March 2012, a waveguide flange which is realized by a bed ofpins, and working between 190 and 320 GHz is proposed. This flange, witha pin structure or a textured surface does not require a conductivecontact when connected to a standard waveguide, which facilitatesfabrication and mounting. The screws need not be tightened very well andit is not needed to assure a good electrical contact as is the case withstandard waveguide flanges. However, it is a disadvantage that it maystill be a difficult and a time consuming operation to fasten the screwsto connect the waveguide flange, even if the requirements as totightening the screws are reduced, and similarly it is time consuming toloosen, remove, the screws at disconnection.

In S. Rahiminejad, E. Pucci, V. Vassilev, P-S.Kildal, S. Haasl, P.Enoksson, “Polymer Gap adapter for contactless, Robust, and fastMeasurements at 220-325 GHz”, Journal of Microelectromechanical Systems,Vol. 25, No. 1, February 2016, a double-sided pin-flange gap adapter isdisclosed which is to be placed between two flanges to avoid leakage. Ithas a drawback in that mechanical contact still is required, although noelectrical contact is needed. The mechanical contact is assured by meansof screws as in other known arrangements, and the adapter has a drawbackin that, if the screws are tightened too much, the adapter may easily bedestroyed, or the adapter can result in pin marks in the sensitiveflange surfaces, which then may be ruined.

Since, as also referred to above, particularly, but not exclusively, forhigh frequencies, for example, from about 10 GHz, or particularly from30 GHz up to about 1 THz, when connecting two waveguide flanges there isrequired a high quality of both mechanical and electrical, or at leastmechanical, contact between the waveguide flanges, in order to obtain ahigh quality, a repeatable and non-radiating interface, and a low lossinterconnection, for example, allowing a good calibration or a reliablemeasurement.

However, the flanges or adapters discussed above have shown not to besuitable for production and operation at, for example, 60 GHz, or from50-75 GHz, which is a wide band. Actually, none of the designs aresuitable for V-band flanges, which is a problem.

Further, in for example, a typical calibration procedure the operatorhas to connect the flanges of calibration standards and ports of a VNA,Vector Network Analyzer, a plurality of times. This is a very timeconsuming, complicated and tedious task, due to all the screws needed toachieve a good contact between all joining flanges. The calibrationprocedure requires a stable and repeatable contact both mechanically andelectrically, or at least mechanically, and therefore four screws shouldalways used, but due to the time consuming and tedious work, sometimesfor example, only two of the required number of screws, for example,four, required to ensure a good electrical contact, are actuallytightened in practice. If the connection is not perfect, for example, ifthere is a slight angular displacement or if there is not a perfect fit,there may be a leakage from the waveguide into free space, and also anincreased reflection at the connection. A calibration procedure, as wellas a measurement procedure, is based on all such connections being asperfect as possible.

Thus, although, through the solutions discussed above, the need for aconductive or electric contact between waveguide structures, orwaveguide flanges, is removed, there is still a need for improvement asfar as waveguide structure interconnecting arrangements are concerned.There is also a need for providing arrangements and structuresappropriate for different and other frequency bands.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anarrangement for interconnection of waveguide structures through whichone or more of the above-mentioned problems can be overcome.

It is particularly an object to provide an arrangement forinterconnection of waveguide structures, which is easy to use andoperate.

It is also an object to provide an arrangement for interconnection ofwaveguide structures which enables interconnection in a fast andreliable manner with a minimum of interconnecting, for example,minimizing screwing and unscrewing, minimizing operations forjoining/disconnecting waveguide flanges, and thereby facilitatinginterconnection, for example, for analysis, calibration or measurementof microwave or millimeter wave circuits or devices.

It is a particular object to provide an arrangement for interconnectionof waveguide structures which can be used for high frequencies, forexample, above 10 GHz, or particularly above 30 GHz, but also for lowerfrequencies without any risk of reduced performance, measurement errorsor calibration errors due to misalignment or leakage betweeninterconnected waveguide structures, for example, waveguide flanges.

It is a particular object to provide an arrangement, and a structurerespectively, appropriate for different, and additional, frequency band,most particularly also for the frequency band 50-75 GHz, for example,for 60 GHz, and even more particularly for interconnection of V-bandflanges.

Particularly, it is an object to provide an arrangement forinterconnection of waveguide structures which is easy and inexpensive tofabricate.

It is a general object to provide an arrangement through whichinterconnection as well as disconnection of waveguide structures isfacilitated.

It is also an object to provide an interconnecting arrangement, and asurface structure, which is robust and suitable with respect tomanufacture for different frequency bands, or independently of which isthe desired frequency band.

Another object is to provide a flexible solution that can be implementedfor interconnection of waveguide structures for operation in differentdesired frequency bands.

A most particular object is to provide an arrangement forinterconnection of waveguide structures which is suitable for being usedfor interconnections, for example, in measurement systems for high aswell as for low frequencies, in connection with different standardwaveguides dimensions (such as WR15, WR12, . . . , WR3) and thecorresponding standard waveguide flange dimensions, and for differentand wide frequency bands.

A particular object is to provide an interconnection arrangement whichcan be used for interconnection of standard waveguide flanges.

A further particular object is to provide an interconnecting arrangementfor connecting an analyzing or measuring instrument to a waveguidecalibration standard or a device under test in such a way that existingcalibration standards can be used and such that connection/disconnectioncan be done in an easier and faster manner than before.

Therefore an interconnecting arrangement as initially referred tocomprises:

-   -   a waveguide flange adapter element having a first waveguide        opening and being configured to provide an interconnection        between first and second waveguide structures;    -   a first waveguide flange of the first waveguide structure having        a second waveguide opening;    -   the waveguide flange adapter element comprising a first surface        of a conductive material with a periodic or quasi-periodic        structure formed by a number of protruding elements surrounding        the first waveguide opening;    -   an interconnector configured to releasably or fixedly        interconnect the waveguide flange adapter element to the first        waveguide flange without requiring electrical contact and to        provide a first gap between a second surface around the first        waveguide opening and the second waveguide opening and provide a        second gap between the first surface and a third surface around        the second waveguide opening assuring that the first surface is        not in direct mechanical contact with the third surface of the        waveguide flange, wherein the number of protruding elements        surrounding the first waveguide opening allow waves to pass        across the first gap in a desired direction or waveguide path,        at least in an intended frequency band of operation, and that        stop propagation of waves in the first gap in other directions;    -   wherein the second gap is smaller than λ/4, where λ is a        wavelength in a medium surrounding the protruding elements of a        waveguide signal to be measured,    -   the interconnector comprises a rim, a ridge, a protective        element or layer, or a supportive element or layer that at least        partly surrounds the periodically or quasi-periodically arranged        protruding elements to provide the second gap; and    -   wherein the waveguide flange adapter element comprises alignment        pin holes substantially symmetrically disposed around, and at a        distance from, the first surface, and the waveguide flange is        aligned with respect to the first waveguide flange by alignment        pins introduced into the alignment pin holes and into        cooperating pin holes in the first waveguide flange to        interconnect the waveguide flange to the first waveguide flange.

Also provided is an arrangement for interconnecting waveguide componentscomprising:

-   -   first and second waveguide flange adapter elements, the first        waveguide flange adapter element comprising a first surface of a        conductive material with a periodic or quasi-periodic structure        formed by a number of first protruding elements surrounding a        first waveguide opening, the second waveguide flange adapter        element comprising a second surface of a conductive material        with a periodic or quasi-periodic structure formed by a number        of second protruding elements surrounding a second waveguide        opening;    -   a first protruding element of the first protruding elements        faces a second protruding element of the second protruding        elements;    -   the facing first and second protruding elements each have a        height or length such that a total height or length of the        facing first and second protruding elements is a full length of        the periodic or quasi-periodic structure needed to stop        propagation of waves inside a second gap between the two        waveguide flange adapter elements in any direction and to allow        waves to pass across a first gap from the first waveguide        opening to the second waveguide opening in an intended frequency        band;    -   an interconnector configured for interconnecting the first and        second waveguide flange adapters elements without requiring        electrical contact and with assuring that the gap is present,        hence assuring that the first surface is not in direct        mechanical contact with the second surface;    -   wherein the second gap is smaller than λ/4, where λ is a        wavelength in a medium surrounding the protruding elements pins        of a waveguide signal to be measured, and    -   wherein the interconnector comprises a rim, a ridge, a        protective element or layer, or a supportive element or layer        that at least partly surrounds surfaces formed by the        periodically or quasi-periodically arranged protruding elements.

Advantageous embodiments are given by the respective appended dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be further described in anon-limiting manner, and with reference to the accompanying drawings,where like features throughout the drawings are denoted by the samereference numbers and in which:

FIG. 1 is a view of an arrangement for interconnection of waveguidestructures comprising a flange adapter element according to a firstembodiment of the present invention,

FIG. 2 shows the flange adapter element of FIG. 1 as connected to awaveguide flange,

FIG. 3A shows the flange adapter element of FIG. 1 arranged in aposition between, and for interconnecting, two waveguide flanges,

FIG. 3B shows the flange adapter element of FIG. 1 in a positionbetween, and for interconnecting, two waveguide flanges as in FIG. 3 Awith interconnecting elements comprising screws with magnetic headsscrewed into the waveguide flanges,

FIG. 3C shows the flange adapter element of FIG. 1 disposed between, andinterconnecting, two waveguide flanges, i.e. in a state in which thewaveguide structures are interconnected,

FIGS. 4A and 4B is a view in perspective of two waveguide flanges, eachwith two alignment pins and screw holes for interconnecting elements,

FIG. 5A shows an alternative embodiment of a flange adapter elementadapted to be fixedly connected to a waveguide flange, and the waveguideflange to which it is connected,

FIG. 5B shows the flange adapter element connected to a waveguide flangeof FIG. 5A in a position for interconnection with another waveguideflange,

FIG. 6A is a view in perspective of another embodiment of a flangeadapter element which comprises protruding elements having a heightcorresponding to half the height of a total texture in a gap structure,

FIG. 6B is a top (also called front) view of the flange adapter elementshown in FIG. 6A,

FIG. 6C is a side view of the flange adapter element in FIG. 6A,

FIG. 7A is a view in perspective of an interconnecting arrangementcomprising two flange adapter elements provided with a periodic orquasi-periodic structure as in FIG. 6A interconnecting two waveguideflanges,

FIG. 7B is a view in perspective as in FIG. 7A, but in anon-interconnected state,

FIG. 7C is side view of the arrangement shown in FIG. 7A in anon-interconnected state,

FIG. 7D is a cross-sectional side view of the arrangement shown in FIG.7A in an interconnected state,

FIG. 8A shows another embodiment of a flange adapter element comprisinggrooves and ridges arranged to form an elliptic pattern around thewaveguide opening and forming the periodic or quasi-periodic structure,

FIG. 8B is a front view of the flange adapter element of FIG. 8A,

FIG. 9A is a view in perspective of a flange adapter element providedwith a periodic or quasi-periodic structure comprising ellipticallydisposed grooves and ridges as in FIG. 8A interconnecting two waveguideflanges,

FIG. 9B is a view in perspective of the interconnecting arrangement andthe waveguide flanges shown in FIG. 9 A but in a non-interconnectedstate,

FIG. 10A is a view in perspective illustrating an exemplary structurecomprising a periodic or quasi-periodic structure of a flange adapterelement or a waveguide flange according to the invention,

FIG. 10B is a top view of the exemplary periodic or quasi-periodicstructure of FIG. 10A,

FIG. 11 is a schematic view in perspective illustrating an alternativestructure of a single-sided flange adapter or waveguide flange accordingto the invention,

FIG. 12 is a schematic view in perspective showing an exemplaryback-to-back flange adapter element with a structure as in FIG. 11,

FIG. 13A is a schematic view in perspective showing an alternativeembodiment of a structure of a back-to-back flange adapter elementaccording to the invention,

FIG. 13B is a schematic front (top) view of the flange adapter elementstructure shown in FIG. 13A,

FIG. 14A is a schematic view in perspective showing a back-to-backflange adapter element with a periodic or quasi-periodic structure ortexture as shown in FIG. 13A,

FIG. 14B is a front view of the flange adapter element of FIG. 14A,

FIG. 15A is a view in perspective showing four interconnecting elementsaccording to an alternative embodiment,

FIG. 15B is a top view of the interconnecting elements of FIG. 15A,

FIG. 15C is a side view of the interconnecting elements of FIG. 15A,

FIG. 16A is a view in perspective of a waveguide flange to which theinterconnecting elements of FIG. 15A are connected but without alignmentpins, and

FIG. 16B is a view in perspective of a flange adapter element connectedto a waveguide flange by means of interconnecting elements as in FIG.14A.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first embodiment of a waveguide structure interconnectingarrangement 100 according to the invention. The waveguide structureinterconnecting arrangement 100 here comprises a flange adapter elementadapted to be disposed between two waveguide flanges, a first waveguideflange 10 connected to a first waveguide 1, and a second waveguideflange 20 connected to a second waveguide 2 (see, for example, FIGS. 2and 3A). The flange adapter element 100 comprises a waveguide flangeelement with a textured surface 15 (also denoted a periodic orquasi-periodic structure) here comprising a number of protrudingelements 15, for example, pins, arranged on a conductive surface to formthe periodic or quasi-periodic structure 15 on one side of the flangeadapter element 100. The periodic or quasi-periodic structure 15 isarranged to surround a rectangular waveguide opening 3, of a throughwaveguide in the flange adapter element, on the cross-sectional sides ofwhich metal rim sections or frame surfaces, also called ridges, areprovided such that two long metal rim or ridge sections 151 are providedon the respective long, wide, sides of the waveguide opening 3 and twoshorter rim or ridge sections 152 are provided on the short or narrowsides of the waveguide opening 3. The height of the rim or ridgesections 151 is here substantially the same as the height of theprotruding elements 15 of the periodic or quasi-periodic structure 15.The longer rim or ridge sections 151 may, for example, have a width ofabout λ_(3/4)/4, λ being the wavelength in in the waveguide structure(not shown to scale in FIG. 1 etc.), or, for example, about 400 μm, andserve the purpose of, together with an opposite smooth waveguide flangewith which the flange adapter element 100 is to be interconnected, forman impedance transformer which transforms an open circuit to a shortcircuit to avoid leakage and reflections which may be created at theinterface between the flange adapter element and the waveguide flange towhich it is to be connected (see waveguide flange 20 in FIG. 3A).

The flange adapter element 100 is adapted to provide an interconnectionbetween two waveguide structures or components, for example, alsoantennas, filters, receivers etc., 10, 20 with conventional smoothwaveguide flanges (see FIGS. 2 and 3A) as will further described below.The smooth surface 4 surrounding the waveguide opening is shown in FIG.2. A protective or supporting element, for example, an outer rim 105, isdisposed such as to surround the periodic or quasiperiodic structure 15,i.e. the textured surface. The purpose of such a protective orsupporting element 105 is to act as a protective distance elementassuring that, when interconnecting or fastening elements press thetextured surface 15 against a waveguide flange with which the waveguideflange is to be interconnected, the pressure will be exerted on theprotective or supporting element 105, and the protruding elements 151 ofthe periodic or quasi-periodic structure will be protected. Further,since the protective or supporting element 105 is arranged to protrude aslight distance beyond the outer ends of the protruding elements 151,the presence of a gap will be assured, and the textured surface isprevented from coming into direct mechanical contact with the opposingwaveguide flange when interconnected, which might lead to the texturedsurface and/or the smooth surface of the interconnecting waveguideflange being damaged or ruined. The flange adapter element 100 comprisesa number of alignment pin receiving holes 101; in the shown embodimentfour, each disposed on a respective wing or flange section protrudingfrom a central section 170 of the flange adapter element 100 where thetextured surface 15 is located, in directions perpendicular to thedirection of extension of the protruding elements 151. The alignment pinreceiving holes 101 serve the purpose of being adapted for receivingalignment pins (for example, FIG. 3A) of waveguide flanges which are tobe connected to the flange adapter element 100 such as to assure thatthe waveguide flanges and the flange adapter element are appropriatelyaligned, and hence the waveguide flanges 10, 20 which are to beinterconnected via the flange adapter element 100. Particularly theflange adapter element can slide on the alignment pins.

Between two respective, opposite, pairs of protruding wing or flangesections, two through recesses, here comprising waists, 103 are formedby flange adapter element side walls, perpendicular to the texturedsurface 15, and tapering towards a central region outside the texturedsurface 15 on respective sides thereof disposed outside the waveguideshort walls 152. Between two respective, opposite, pairs of protrudingwing or flange sections two through recesses 102 are formed by flangeadapter side walls, which are perpendicular to the textured surface 15.The recesses 102 are here substantially U-shaped with a substantiallystraight section interconnecting the legs of the U's and located outsidethe textured surface at locations extending substantially in parallelwith the long sides of the waveguide opening 3. The waist shapedrecesses 103 and the U-shaped recesses 102 are so shaped, and have suchdimensions, as to allow an interconnecting element 12 (for example, FIG.2) to be located therein, for example, connected to the surface of arespective waveguide flange 10, 20, for example, a standard waveguideflange, whereas the circumferential outer side walls of the wing orflange sections of the flange adapter element 100 are so shaped and havesuch dimensions as to correspond to the circumferential, peripheral,side walls of the respective waveguide flanges. The positions of thewaists and U-shaped recesses are preferably so chosen that theycorrespond to locations where fastening screw holes are located instandard waveguide flanges.

The flange adapter element 100 preferably comprises a solid part made ofbrass, Cu, Al or any other appropriate material with a goodconductivity, a low resistivity and an appropriate density. It may, forexample, be plated with Au or Ag in environments where further corrosionprotection is needed. It should be clear that also other materials canbe used, for example, any appropriate alloy. It can also be fabricatedfrom a suitable plastic/polymer compound and plated with, for example,Cu, Au or Ag.

The flange adapter element 100 in the shown embodiment comprises aflange element on a central portion of which a periodical orquasi-periodic structure, also denoted a texture, 15 is disposed aroundthe opening of a standard rectangular waveguide 3. It should be clearthat in alternative embodiments the flange adapter element may have anyother appropriate shape, allowing it to be connected between, forexample, two waveguide flanges, a waveguide flange and an antenna oranother device, a waveguide flange of a calibrating arrangement, a DUT(Device Under Test) etc. It may in different embodiments be provided asa separate flange adapter element, in other embodiments it may beadapted to be fixedly connected to a waveguide flange (for example, FIG.5A), or in still other embodiments be adapted to be connected to anotherflange adapter element (for example, FIG. 6A). It may also form awaveguide flange.

The texture, for example, the periodic or quasi-periodic structure, 15may comprise a structure comprising a plurality of protruding elements,for example, pins 151 having a square shaped cross-section, but theprotruding elements can also have other cross-sectional shapes such ascircular or rectangular, comprise a corrugated structure, for example,comprising elliptically disposed grooves and ridges as shown in FIGS.8A, 8B, 9A and 9B. Other alternative shapes for corrugations are alsopossible.

Through providing a connection between a conductive smooth flangesurface or plane of a waveguide 20 (see FIG. 3A) on one side and aflange surface with a periodic or quasi-periodic structure 15 on theother side, the two waveguides (for example, a waveguide and a waveguideof an object to be measured or a waveguide of a calibration standard, awaveguide calibration standard and a VNA waveguide port etc.) can beconnected without requiring electrical contact, but also without directmechanical contact. The presence of a gap 30B (see FIG. 7D), forexample, of air, or a gap filled with gas, vacuum, or at least partlywith a dielectric material, between the two connecting flange surfacesis allowed since the periodic or quasi-periodic structure stops all kindof wave propagation between the two flange surfaces in all otherdirections than desired waveguiding paths. The periodic orquasi-periodic structure 15, or texture, is, as also referred to above,so designed that the structure 15 stops propagation of waves inside thegap 30 in any direction, whereas waves are allowed to pass across thegap from the waveguide opening in one flange surface to the waveguideopening in the other, at least in the intended frequency band ofoperation. Thus, the shapes and dimensions and the arrangement of, forexample, pins, posts, grooves, ridges etc. of the periodic orquasi-periodic structure are selected such as to prevent propagation ofwaves in any direction other than the intended direction.

The non-propagating or non-leaking characteristics between two surfacesof which one is provided with a periodic texture (structure), is knownfrom P-S.Kildal, E. Alfonso, A. Valero-Nogueira, E. Rajo-Iglesias,“Local metamaterial-based waveguides in gaps between parallel metalplates”, IEEE Antennas and Wireless Propagation letters (AWPL), Volume8, pp. 84-87, 2009 and several later publications by these authors. Thenon-propagating characteristic appears within a specific frequency band,referred to as a stopband. Therefore, the periodic texture and gap sizemust be designed to give a stopband that covers with the operatingfrequency band of the standard waveguide being considered in thecalibration kit. It is also known that such stopbands can be provided byother types of periodic structures, as described in E. Rajo-Iglesias,P-S.Kildal, “Numerical studies of bandwidth of parallel plate cut-offrealized by bed of nails, corrugations and mushroom-type EBG for use ingap waveguides”, IET Microwaves, Antennas & Propagation, Vol. 5, No3_(A) pp. 282-289, March 2011. These stopband characteristics are alsoused to form so called “gap waveguides” as described in Per-SimonKildal, “Waveguides and transmission lines in gaps between parallelconducting surfaces”, patent application No. PCT/EP2009/057743, 22 Jun.2009.

It must be emphasized that any of the periodic or quasi-periodictextures previously used or that will be used in gap waveguides also canbe used in a waveguide structure interconnecting arrangement, a flangeadapter element or flange structure of the present invention, and iscovered by the patent claims.

The concept of using a periodic texture to improve waveguide flanges isknown from P-S.Kildal, “Contactless flanges and shielded probes”,European patent application EP 12168106.8, 15 May 2012.

According to the present invention, the two surfaces, for example, thetextured structure of the flange adapter element or a flange element,i.e. the plane formed by the free outer ends of the pins or ridges orsimilar of a periodic or quasiperiodic structure, and a smooth waveguideflange, or another textured surface, must not be separated more than aquarter of a wavelength of a transmitted signal, or rather have to beseparated less than a quarter wavelength. This is thoroughly describedin the above-mentioned publications, such as in particular in E.Rajo-Iglesias, P.-S. Kildal, “Numerical studies of bandwidth of parallelplate cut-off realized by bed of nails, corrugations and mushroom-typeEBG for use in gap waveguides”, IET Microwaves, Antennas & Propagation,Vol. 5, No 3, pp. 282-289, March 2011.

The periodic or quasi-periodic structure 15 in particular embodimentscomprises an array of pins 151 with a cross section, for example, havingthe dimensions of 0.15λ×0.15λ and a height of 0.15λ-0.25λ.

Through the provisioning of an interface formed by a smooth conductivesurface of a waveguide flange 20 on one side of the interface and atextured surface 15 on the other side of the interface, power isprevented from leaking through the gap between the smooth conductivesurface and the textured surface, or between two textured surfaces (seein particular embodiments described with reference to FIGS. 6A, 6B, 6C,7A, 7C and 7D). Propagation in non-desired directions is prohibited bymeans of a high impedance, resulting from the provisioning andarrangement of a periodic or quasi-periodic structure.

According to the invention, by using a combination of a surfacecomprising a periodic or quasi-periodic structure 15 and a waveguideflange 20 with a smooth conductive surface, or two surfaces eachprovided with a periodic structure (see, for example, FIGS. 7A-7D asdiscussed above) waveguides can hence be connected also without thesurfaces having to be in electrical contact, and through the use of aprotective or supportive rim 105 also no direct mechanical or physicalcontact is required which in turn relieves the requirement of a tightfastening by means of screws or similar to interconnect the surfaces,and the flange surfaces are protected.

Particularly the texture is designed to provide a stopband for wavesleaking out between the two joining flanges, even when there is a smallgap between the textured flange surface and the opposite flange surface,and also so that waves passing from the waveguide opening in one flangeto the waveguide opening in the joining flange are not affected so thatthe transmission and the reflection from the joint is very close to thetransmission and the reflection when conventional waveguide flanges arejoined together, interconnected, very tightly by screws which are drawnvery tight. As also referred to above, the texture can be made by pins,ridges or grooves etc. disposed around the waveguide opening in apattern which is optimized to provide a good performance in terms of alow leakage, and improving, enhancing, the transmission coefficientwhich is reduced due to there being a discontinuity caused by the smallgap between the two joining waveguides, and reducing the reflectioncoefficient which is increased due to there being a discontinuity causedby the small gap between the two joining waveguides.

PCT application PCT/SE2016/050277 with priority from Swedish patentapplication 1550412-9, filed on 4 Apr. 2015 by the same Applicant as forthe present application, and the content of which herewith isincorporated herein by reference, shows an arrangement for connecting ananalyzing or measuring instrument to a waveguide calibration standard ora device under test, and a calibration arrangement for a tool orinstrument for analyzing or measuring microwave circuits or devices. Itcomprises a calibration connector element in the form of a disk or platewith a waveguide opening in it to be located between two joiningwaveguide flanges, allowing contactless connection between the twowaveguide flanges, one of which being the port of the analyzing ormeasuring instrument, for example, a Vector Network Analyser (VNA), andthe other being the port of either a waveguide calibration standard or adevice under test. The calibration connector element comprises twosurfaces, one on each side of it, each of which has a periodic orquasi-periodic structure around the waveguide opening forming a firstand a second periodic or quasi-periodic structure. It is connectablebetween the waveguide flanges in such a way that on each side of it agap is formed between the periodic or quasi-periodic structure and thesmooth surface of the corresponding flange, hence allowinginterchangeable contactless interconnection of a waveguide of theanalyzing or measuring instrument, for example, a VNA, and a waveguidecalibration standard or a device under test comprising a waveguide port.

FIG. 2 shows the flange adapter element 100 of FIG. 1 connected to awaveguide flange 10 of a first waveguide structure 1. The waveguideflange 10 is here supposed to be a standard waveguide flange, forexample, a V-band flange, a WR15 flange, or any other standard waveguideflange. Such a standard waveguide flange 10 normally comprises fouralignment pin holes 110, not visible in FIG. 2; cf. FIG. 3A, forreception of alignment pins, and four screw holes 120 adapted forreception of fastening screws. According to the present invention theflange adapter element 100 is releasably connected to the standardwaveguide flange 10 and aligned, and can slide, with respect thereto bymeans of two alignment pins introduced into two respective, oppositelydisposed, alignment pin holes 110 of the standard waveguide flange 10and the corresponding alignment pin holes 101 in the wing sections ofthe flange adapter element 100. Interconnecting elements 12 in the formof screws with heads having magnets 13, in the following also simplydenoted magnetic screw heads, or magnetic elements on the screw heads,are introduced into the screw holes 120 of the standard waveguide flange10, and the through recesses, waists 103 and U-shaped recesses 102, offlange adapter element 100 are so located and have such sizes as toallow reception of the screw heads 13. The height of the head of eachscrew 12 substantially corresponds to half the thickness of the flangeadapter element 100. In some embodiments the magnetic elements comprisesmall elements fastened to the flat surface of the screw heads, forexample, by means of gluing or in any other appropriate manner as alsowill be further discussed below. The screw heads may also comprisemagnetic head portions. Elements shown in FIG. 2 which already have beendescribed with reference to FIG. 1 will not be further discussed withreference to FIG. 2.

FIG. 3A illustrates two waveguide structures 1, 2, comprising twostandard waveguide flanges 10, 20 in a position for being interconnectedby means of a flange adapter element 100 as described with reference toFIGS. 1 and 2. The flange adapter element 100 and the first standardwaveguide flange 10 have already been described with reference to FIGS.1 and 2 and will therefore not be further described herein. The secondstandard waveguide flange 20 is in the shown embodiment similar to thefirst standard waveguide flange 10 and comprises four alignment pinholes 120 and four fastening element or screw holes 220. Two alignmentpins 111 are in a positions for being introduced into two correspondingalignment pin holes 101 and 110 of the first standard waveguide flange10 and the flange adapter element 100 respectively. The respective pinholes that are used for alignment of the flange 10 and the flangeadapter element 100 are oppositely disposed, and the remaining twoalignment pin holes 101 of the flange adapter element 100 are used forreception of two further alignment pins 111 which in the other ends areintended to be received in corresponding alignment pin holes 210 of thesecond waveguide flange 20. Four screws 12 with magnetic heads 13 are ina position for being introduced into four screw holes 120 of the firstwaveguide flange 10, and four other screws 22 with magnetic heads 23 arein a position for being introduced into four screw holes 220 of thesecond waveguide flange 20. The screws 12, 22 with the magnetic heads13, 23 are so disposed that interconnection can be achieved by means ofa snap-on like operation, clamping the flange adapter element 100between the first and the second waveguide flanges 10, 20. It is anadvantage that the flange adapter element 100 can slide on the alignmentpins 111 that the joining flanges are movable in relation to each otherthrough the gap and in particular embodiments need not be centralizedwith respect to the stop band. In one embodiment the magnetic elements13, 23 comprise neodymium magnets, (NdFeB) which are strong permanentmagnets. Of course also other magnetic materials with similar propertiesmay be used, this is merely to be seen as an example. The surface may,for example, be Ni-plated or plated with some other appropriatematerial. In some embodiments the screw heads of conventional screwsused for fastening of waveguide flanges are provided with smallpermanent magnets.

The flange adapter element particularly is solid and made in one piecein order not to influence the signal flow. It may, for example, be madeby molding, casting, ablation, material assembling, for example,micro-assembling and cutting is another method.

FIG. 3B illustrates the two waveguide structures 1, 2, comprising twostandard waveguide flanges 10, 20 in a position for being interconnectedby means of the flange adapter element 100 as in FIG. 3A, but with theinterconnecting elements, screws 12, 22, introduced into the screw holes120, 220 of the first and second waveguide flanges 10, 20. When thewaveguide flanges 10, 20 are brought in contact with the flange adapterelement 100, with the screws 12, 22 positioned in the recess sections,i.e. here the U-shaped recesses 102 and the waist sections 103, thewaveguide flanges will be forced towards each other and be joined orinterconnected by means of the magnetic force between the magnetic screwheads 13, 23. Due to the alignment pins 111 the positioning will beaccurate. Thus, interconnection takes place in an easy manner, like asnap-on operation. Although screws are still needed, they can, forexample, easily be applied or introduced into the screw holes of thewaveguide flanges 10, 20 on beforehand. There is also no need to tightenany screws. Once the screws have been applied to the waveguide flanges,and they are brought in position on opposite sides of a flange adapterelement 100, the interconnection will take place in an almost automaticmanner without requiring any particular skill of the personnel handlingthe assembly. Thereby interconnection (joining), removal, replacement ofwaveguide structures, or waveguide flanges, is considerably facilitatedand can be done in an easy and fast manner, with a high accuracy andwithout needing to exert strong forces resulting in the risk of ruiningthe textured surface, or the smooth surface of the opposing flange.

In FIG. 3C a state in which the first and second waveguide flanges 10,20 are interconnected or joined by means of interposition of the flangeadapter element 100 and held together by means of the magnetic heads 13,23 (shown in FIGS. 3A and 3B) of the interconnecting screws 12, 22, andaligned by means of the alignment pins 111 as discussed above. Theslight gap between the periodic or quasi-periodic structure 15 and thesmooth surface of the second waveguide flange 20 cannot be seen in FIG.3C due to the presence of the protective or supporting element 105 (seeFIG. 1) which is in contact with the smooth surface of the secondwaveguide flange 20.

FIGS. 4A and 4B show a schematic view in perspective serving the purposeof illustrating the first and second waveguide flanges 10, 20, each withtwo alignment pins 111 introduced into two respective alignment pinholes 110, 210. As can be seen two diametrically disposed alignment pinholes of each waveguide flange are used, and alignment pin holes withdifferent positions are used in the first and second waveguide flanges10, 20, such that, when interconnected by means of flange adapterelement, all four holes of the flange adapter element 100, whereas onlytwo each of the alignment pin holes of the waveguide flanges 10, 20 areused. In other respects the elements shown in FIGS. 4A and 4B havealready been discussed with reference to the preceding figures.

FIG. 5A shows an alternative embodiment of a waveguide structureinterconnecting arrangement 100A which here comprises a flange adapterelement structure 100A adapted to be fixedly or releasably connected toa waveguide flange 10A, for example, a standard waveguide flange 10A. Itis fastened to the waveguide flange 10A by means of fastening screws 17introduced into the waveguide flange 10A in a direction towards thewaveguide flange adapter element 100A. The flange adapter elementstructure 100A comprises a waveguide adapter element main body 140Asubstantially as described with reference to FIGS. 1-4, but which isintegral with, or made in one piece with, or connected to, a flangeadapter support element 145A preferably with the same cross section as awaveguide flange 10A and having a thickness allowing the first waveguideflange 10A to be fixedly (or removably) connected thereto by means inthe conventional art of fastening screws 17. Alternatively, the flangeadapter element structure 100A can be connected to the waveguide flange10A in any other appropriate manner, the flange adapter elementstructure 100A might even be glued onto the waveguide flange 10A in someembodiment alternative. In the through recess sections 102A, 103A (heresimilar to the corresponding sections 102, 103 described with referenceto FIGS. 1 and 3A) and on a surface of the flange adapter supportelement 145A on which the part of the flange adapter element structure100A is provided which correspond to the flange adapter element, forexample, as described with reference to FIG. 1, magnetic elements 13Aare provided. In the shown embodiment the magnetic elements 13A arefixedly mounted in recesses designed therefore in the flange adaptersupport element 145A such as to not protrude from the outer surface offlange adapter support element 145A, i.e. contiguous therewith. Forinterconnection to a second waveguide flange (see FIG. 5B) as describedwith reference to FIGS. 3A-3D, either screws with magnetic heads as inan embodiment described with reference to FIGS. 3A-3D would have to haveheads with a thickness of approximately twice the thickness in order toallow interconnection, or the flange adapter element main body 140Awould have to have a thickness of about half the thickness of the flangeadapter element 100 in FIG. 1, the flange adapter main body 140A beingthinner. In still other embodiments (not shown) the magnetic elements 13A are disposed such as to be located at about half the height of theflange adapter element main body 140A, for example, disposed onshoulders or similar on the surface of the flange adapter supportelement 145A. Still further the magnetic elements may have a heightsubstantially corresponding to a magnetic screw head as described aboveor comprise a magnetic surface provided on mounting elements havingsubstantially such a height. Many variations are possible.

FIG. 5B illustrates the flange adapter element structure 100 A of FIG.5A as mounted on a first waveguide flange 1 OA in a position for beinginterconnected with a second waveguide flange 20A with a smooth surfaceas described with reference to FIGS. 3A, 3B, 3C and 3D. Since thefunctioning as far as the interconnection or joining to a secondwaveguide flange 20A corresponds to that described with reference toFIGS. 3A, 3B, 3C, and 3D, this will not be further described herein.

It is an advantage that, allowing a flange adapter to be fastened, forexample, by screws, to a waveguide flange, the flange adapter will bekept in place, there is no risk of losing it, and it will not fall off.

In the embodiments shown in FIGS. 6A, 6B, 6C, 7A, 7B, 7C and 7D, twoflange adapter elements 100B₁ (FIG. 6A), 100B₂ (FIG. 7A) are connectedtogether and referred to as 100B (FIG. 7A). FIG. 6A, 6B and 6C showdifferent views of the flange adapter element 100B₁ and the flangeadapter element 100B₂ is the same as 100B₁. The two flange adapterelements 100B₁, 100B₂ (FIG. 7A) are adapted to be disposed between, and,fixedly or detachably, connected to each a waveguide flange 10B, 20B asshown in FIG. 7A. The flange adapter element 100B₁ comprises a waveguideflange element with a textured surface 15B (FIGS. 6A and 7B), here witha number of protruding elements 115B, for example, pins, arranged on aconductive surface to form a periodic or quasi-periodic structure on oneside of the flange adapter element 100B₁ as described with reference tothe preceding embodiments. The periodic or quasi-periodic structure 15B(FIGS. 6A and 7B) is arranged to surround a rectangular waveguideopening 3B (FIGS. 6A and 6B) on the sides of which metal rim or ridgesections 151B, 152B (FIGS. 6A and 6B) are provided. Two shorter rim orridge sections 152B are provided on the waveguide opening short ornarrow sides. On each wide or long side of the waveguide opening 3B along metal rim or ridge section 151B is provided. In the shownembodiment the long rim or ridge section 151B has a first a first wallthickness d₁ substantially being λg/4, λg being the wavelength in thewaveguide structure, extending along the central, major, part of thewaveguide wide or long side, and a second wall thickness d₂ width at theouter ends of the waveguide long side, wherein d₂ is smaller than d₁(FIG. 6B). A reason for the different thicknesses is to improve thecapability of covering a wide frequency band avoiding resonances withinthe band, see also FIGS. 11, 12, 13A, 13B, 14A and 14B where theexemplary structure is more thoroughly discussed. In other embodiments,however, a same wall thickness may be used, for example, as shown inFIG. 1, although not to scale in FIG. 1. Other alternatives are alsopossible.

The height of the frame or rim sections 151B, 152B is substantially thesame as the height of the protruding elements 115B of the periodic orquasi-periodic structure 15B.

The flange adapter element 100B₁ is adapted be connectable, fixedly orremovably, to a standard waveguide flange 10B (cf. FIGS. 7A, 7B) to,allow it to be joined or interconnected with a second, similar, flangeadapter element 100B₂ connectable, fixedly or removably, to, forexample, a second standard waveguide flange 20B, hence providing aninterconnection between the two waveguide structures 1B, 2B (FIGS. 7A,7B) with conventional smooth waveguide flanges.

The flange adapter element 100B₁ comprises a central portion 170Bprovided with a periodic or quasi-periodic structure 15B comprising aplurality of protruding elements 115B, a textured surface, disposedaround the opening of a standard rectangular waveguide opening 3B. Inthis embodiment the pins or protruding elements 115B each has a height,or length, corresponding to substantially half the total length of thepin or protruding element required to form the desired stop band. Thetotal height is formed by the two flange adapter elements 100B₁, 100B₂disposed such that the textured surfaces face one another, and the totallength being formed by two corresponding protruding elements 115B, oneon each flange adapter element (see FIGS. 7A, 7B).

In still other alternative embodiments different heights are used forthe sets of pins or protruding elements or corrugations on flangeadapter elements. In yet other embodiments the lengths or heights of thepins or protruding elements, or corrugations, vary within the respectivesets (not shown), as long as the total length of one another facing, oroppositely disposed, pins, protruding elements or corrugationscorresponds to a length required for the desired stop band. Suchdifferent arrangements of protruding elements are disclosed in theEuropean patent application “Waveguide and transmission lines in gapsbetween parallel conducting surfaces”, EP15186666.2, filed on 24 Sep.2015 by the same Applicant, the content of which herewith isincorporated herein by reference, and which shows a microwave devicewhich comprises two conducting layers arranged with a gap there between,wherein each of the layer comprises a set of complementary protrudingelements, arranged in a periodic or quasi-periodic pattern and connectedthereto, and which sets in combination for a texture for stopping wavepropagation in a frequency band of operation in other directions thanalong intended waveguiding paths. When the lengths of the protrudingelements are the same, and the full length of the texture being formedby two protruding elements arranged on each a conducting layer, thelength of a protruding element hence corresponding to half the length ofthe full-length of the protruding elements of the texture.

Generally, throughout the application, the length of a full-lengthprotruding element is approximately between λ/4 and λ/2, and the heightof a so called “half-length element,” is substantially between λ/8 andλ/4, λ being the wavelength in free space or a dielectric media.

The flange adapter element 100B₁ further comprises pairwise oppositelydirected wing sections 175B, 176B extending in four directions from thecentral portion 170B which here has a substantially octagonalcross-sectional shape. Each wing section 175B, 176B is provided with ascrew hole 102B adapted to receive an interconnecting screw 12B with amagnetic head (or screw head with a magnetic element as also discussedabove) 13B (see FIG. 7B) for connection to a waveguide flange (FIG. 7A),and, via the magnetic head 13B, releasable interconnection with anothermagnetic head (or screw head with a magnetic element) 23B (FIG. 7B) of ascrew 22B (FIG. 7B) connecting the second, or other, flange adapterelement 100B₂ to the second waveguide flange 20B (FIG. 7B). Thethickness of the wing sections is such that, together with the height ofthe head of the interconnecting screw 12B (FIG. 7B), the length or theheight of the protruding elements 115B is slightly exceeded, leaving aslight air gap between one another facing protruding elements 115B onthe respective flange adapter element 100B₁, 100B₂.

The air gap is smaller than λ/4, and the height of the protrudingelements 115B, here half-length elements, is for example, substantiallyλ/8.

FIG. 6B is a top, or front, view of the flange adapter element 100B₁shown in FIG. 1 illustrating the wall thicknesses d₁, d₂ of the long rimor ridge section 151B.

FIG. 6C is a side view in cross-section of the flange adapter element100B₁ shown in FIG. 1.

In alternative embodiments the opposite pairs of protruding wing orflange sections have shapes as disclosed with reference to FIG. 1, withthe difference that the opposite pairs of protruding wing or flangesections have to be thinner for half-height protruding elements, or beadapted depending on the lengths of cooperating protruding elementstogether forming a full-height protruding element, such as to leave roomfor magnetic screw heads, while keeping a slight gap between theprotruding elements on two for the interconnection cooperating flangeadapter elements.

FIG. 7A illustrates two waveguide flanges 10B, 20B interconnected bymeans of two flange adapter elements 100B₁, 100B₂ as discussed withreference to FIGS. 6A-6C. Since the different elements and parts havealready been discussed above, they will not be further discussed withreference to FIG. 7A. The distance between the flange gap adapters, theair gap, may, for example be about 100 μm.

FIG. 7B is a view in perspective showing the two waveguide flanges 10B,20B to which each a flange adapter element 100B₁, 100B₂ is connected bymeans of the screws 12B in a position for being interconnected throughthe magnetic heads 13B, 23B or magnetic elements or portions on thescrew heads 12B, 22B as discussed above.

FIG. 7C is a schematic side view showing the two waveguide flanges 10B,20B to which each a flange adapter element 100B₁, 100B₂ is connected bymeans of the screws 12B, 22B in the position for being interconnectedthrough the magnetic attraction between magnetic heads 13B, 23B as shownin FIG. 7B.

FIG. 7D is a schematic cross-sectional side view showing the twowaveguide flanges 10B, 20B to which each a flange adapter element 100B₁,100B₂ is connected by means of the screws 12B (FIG. 7C), 22B in aninterconnected state as in FIG. 7 A illustrating the gap 30B between theperiodic or quasi-periodic structures of the flange adapter elements100B₁, 100B₂.

A particular advantage with the use of half-height protruding elementsis that only one type of flange or flange adapter element is neededinstead of two different types involved in an interconnection, as forexample in the case of a textured flange adapter element, as a separateelement or fixed to, or forming part of, a waveguide flange, or a flangewith such a texture, and a waveguide flange with a smooth surface. Thusgender-less flange adapter elements or waveguide flanges can beprovided.

It should also be clear that the pattern of the textured surface, of theprotruding elements forming the periodic or quasi-periodic structure,can be different, for example as shown with reference to FIG. 1, or thestructure of the embodiment in FIG. 1 may be as shown in FIG. 6A etc.Any variation is possible, and will be further discussed with referenceto FIGS. 10A, 10B, 11, 12, 13A, 13B, 14A and 14B below.

The flange adapter element 100B preferably comprises a solid part madeof brass, Cu, Al or any other appropriate material with a goodconductivity, a low resistivity and an appropriate density. It may, forexample, be plated with, for example Au or Ag, in environments wherefurther corrosion protection is needed. It should be clear that alsoother materials can be used, for example, any appropriate alloy, or aplastic/polymer compound plated with, for example, Cu, Au or Ag.

FIG. 8A is a perspective view of a waveguide structure interconnectingarrangement 100C according to still another embodiment and comprising aflange adapter element 100C. Similar to the embodiment described withreference to FIG. 1, the flange adapter element 100C is adapted to bedisposed between two waveguide flanges 10C, 20C (see FIGS. 9A, 9B). Theflange adapter element 100C comprises a textured surface 15C, here witha number of protruding elements comprising a number of grooves andridges 115C, for example two or three, or in some cases more,elliptically disposed around the waveguide opening 3C on a conductivesurface to form a periodic or quasi-periodic structure on one side ofthe flange adapter element 100C. The depth of the grooves 115C is aboutλ/4 for a full-height implementation as shown in FIG. 8A forinterconnection with a waveguide flange with a smooth surface, and aboutλ/8 for half-height implementations as described with reference to FIGS.6A, 6B, 6C, 7A, 7B, 7C and -7D but formed by a texture comprisingelliptically arranged grooves (not shown).

The flange adapter element 100C is adapted to provide an interconnectionor joint between two waveguide structures with conventional smoothwaveguide flanges 10C, 20C (see FIGS. 9A, 9B). A protective orsupporting element, for example a rim, 105C is arranged to surround theperiodic or quasiperiodic structure 15C, i.e. the textured surface, andthe rim 105C acts as a protection of the protruding ridges between thegrooves and can be said to act as a distance element assuring that, wheninterconnecting or fastening elements press the textured surface 15Cagainst a waveguide flange with which it is to be interconnected, thepressure will be exerted on said protective, solid, surface, and theprotruding elements, ridges, 115C between the grooves will be protected,as well as the interconnecting smooth flange surface. Since theprotective or supporting element 105C is arranged to protrude a slightdistance beyond the outer ends of the protruding elements, here the topsof the ridges, the presence of a gap will be assured, and the texturedsurface does not come into direct contact with the opposing waveguideflange 20C (FIGS. 9A, 9B) when fastened or interconnected.

The flange adapter element 100C comprises a number of alignment pinreceiving holes 101C; in the shown embodiment four, which are providedin a respective wing or flange section protruding from a central section170C of the flange adapter element 100C where the textured surface 15Cis located, in directions perpendicular to the direction of extension ofthe protruding elements 115C. The alignment pin receiving holes 101Cserve the purpose of being adapted for receiving alignment pins (forexample, FIG. 9B) of waveguide flanges which are to be interconnectedsuch as to assure that the waveguide flanges 10C, 20C and the flangeadapter element 100C are appropriately aligned, and allowing sliding.

Between two respective, opposite, pairs of protruding wing or flangesections, through recesses, here, waists 103C are formed by flangeadapter side walls, perpendicular to the textured surface 15C, taperingtowards a central region outside the textured surface 15C on arespective side thereof disposed outside the waveguide opening 3C shortor narrow side walls. Between two respective, opposite, pairs ofprotruding wings or flange sections through recesses 102C are formed byflange adapter side walls perpendicular to the textured surface 15C,which recesses are substantially U-shaped with a substantially straightsection interconnecting the legs of the U and located outside thetextured surface 15C at locations extending substantially in parallelwith the long, wide, sides of the waveguide opening 3C. The waist shapedrecesses 103C and the U-shaped recesses 102C are so shaped, and havesuch dimensions, as to allow a fastening element 12C, or a head thereof,(cf. FIG. 9B) to be connected to the surface of a respective waveguideflange 10C (FIG. 9B), for example a standard waveguide flange, whereasthe circumferential side walls of the wing or flange sections flangeadapter element 100C are so shaped and have such dimensions as tocorrespond to the circumferential, peripheral, side walls of therespective waveguide flanges 10C, 20C. The positions of the waists andU-shaped recesses 102C, 103C are preferably so chosen that theycorrespond to locations where fastening screw holes are located forstandard waveguide flanges.

FIG. 8B is a top view of the flange adapter element 100C of FIG. 8A, theelements of which already have been discussed above.

FIG. 9A shows the flange adapter element 100C disposed between twowaveguide flanges 10C, 20C and in which the latter are interconnectedthereby and through interconnecting screws 12C, 22C with magnetic heads13C, 23C or with magnetic elements on the heads. FIG. 9A is similar toFIG. 3C but for a flange adapter element as in FIGS. 8A, 8B and hencewith reference numerals as in FIGS. 8A, 8B, with reference to which alsoall elements have been discussed above.

FIG. 9B illustrates the two waveguide flanges 10C, 20C in a position forbeing interconnected by means of the flange adapter element 100C, andwith the interconnecting elements, screws 12C, 22C introduced into thescrew holes 120C, 220C of the first and second waveguide flanges 10C,20C. When the waveguide flanges 10C, 20C with the screws with magneticheads 13C, 23C introduced into the screw holes are brought into contactwith the flange adapter element 100C, such that the screw heads 13C, 23Care positioned in the through recess sections, i.e. here the U-shapedrecesses and the waist sections, they will be automaticallyinterconnected by means of the magnetic attraction between the magneticscrew heads 13C, 23C. By means of the alignment pins 111 the positioningwill be accurate. Thus, interconnection takes place in an easy manner,like a snap-on operation. Although screws may still be needed, they can,for example, easily be applied or introduced into the screw holes of thewaveguide flanges 10C, 20C on beforehand as also referred to above withrespect to the embodiment shown in FIGS. 1, 2, 3 and 4. There is also noneed to tighten any screws. Once the screws with magnetic heads, ormagnetic elements on the heads, have been applied to the waveguideflanges, and they are brought in position on opposite sides of a flangeadapter element 100C, the interconnection will take place in an almostautomatic manner without requiring any particular skill of the personnelhandling the assembly. Thereby interconnection, joining, removal,replacement of waveguide structures, or waveguide flanges, isconsiderably facilitated and can be done in an easy and fast manner,with a high accuracy and without needing to apply strong forcesresulting in the risk of ruining the textured or smooth flange surfaces.The height of the screw head have already been discussed with referenceto the embodiments presented in FIGS. 1, 2, 3, and 4, and the sameconditions apply for embodiments with other textured surfaces, such as acorrugated structure, a structure with elliptic grooves etc. as alsoreferred to above. Other examples are structures corresponding toembodiments as disclosed in FIGS. 5A, 5B, with a flange adapter elementstructure adapted for being fixedly connected to a waveguide flange, orbe formed as a waveguide flange itself, or arranged for interconnectionwith another flange adapter element in which case both flange adapterelements are provided with half-height protruding elements of any kind,or, with protruding elements of such lengths as to in a cooperatingpair, form a full-height protruding element, but with a gap betweenthem.

In the following description some different textured surfaces andsurrounding rim or ridge sections will be described, applicable to anywaveguide flange adapter element or waveguide flange etc.

FIG. 10A shows the central portion or structure 170 with a texturedsurface 15 of a flange adapter element as in FIG. 1 but here for aback-to-back flange adapter element; the functioning of the periodic orquasi-periodic structure however being the same irrespectively of thestructure being a back-to-back implementation or a single-sidedimplementation. The textured surface, or the periodic or quasi-periodicstructure, 15 here comprising pins 115 arranged for interconnection withan opposed smooth flange surface located such that there is a small airgap there between preventing waves from propagating in the gap betweenthe surfaces. The condition for the stopband is imposed by the height ofthe pins 115, which may be around λ/4, λ being the wavelength in themedia surrounding the pins, which is normally free space, but can alsobe a dielectric media.

The pins 115 can be thick or thin. Thick pins are preferable from amanufacturing point of view. A larger pin thickness to pin height ratiomakes the production easier. However, standard flanges have a fixedsize, so that there is a limited space to fit the pins into the standardflange, and each row of pins introduces an attenuation for the wavespreventing them from leaking out. Therefore, thin pins are preferablefor a better performance of the flange, that is, for having lessleakage. The inventive concept covers the use of thick as well as thinpins, or other protruding elements which are thick or thin.

As also mentioned with reference to FIG. 1, the rim or ridge 151, 152around the waveguide 3 opening is important for the electricalperformance of the waveguide flange, and the dimensions therefore shouldnot be selected arbitrarily. Also, fabrication aspects need to beconsidered. E. Pucci, P-S.Kildal, “Contactless Non-Leaking waveguideflange Realized by Bed of Nails for millimeter wave Applications”,6^(th) European Conference on Antennas and Propagation (EUCAP), pp.3533-3536, Prague, March 2012, as also referred to in the state of theart section, discloses the use of a ridge around the waveguide opening.This ridge has the same height as the pins have, and is much thickeralong the wide side of the waveguide opening, and is referred to as an“Impedance Transformer”. This thickness is about λ_(3/4)/4, whichtransforms an open circuit in a short circuit at the waveguide opening,in such way that the waves “see” a metal wall or electric contact evenif physically there is a gap between the flanges where the waves couldcome in. A similar textured structure is used in some embodiments, forexample with a difference that there is one more, shorter, row of pinsoutside the outermost row on the wide sides of the waveguide opening andthat the walls of the short rims or ridges 152 are somewhat thicker.

In FIG. 10B a top, or front, view of the textured structure 15 is shown.

The designs presented by Pucci et.al showed to not be suitable to beproduced at 60 GHz. One of the designs of the ridge is a rectangular rimwith a thickness of λ_(δ)/4 along the wide walls of the waveguideopening, and has a thickness of only 50μιη or even less along the narrowwalls of the waveguide opening. Such a thickness is not appropriate froma manufacturing point of view. If on the other hand the thickness isincreased, then it is not possible to cover the whole V-band of standardflanges (from 50 GHz to 75 GHz), which is a very wide band. This is dueto a resonance appearing within the band.

Another design of a ridge around the waveguide opening is a circular rimthat was used for a 200-300 GHz flange described in In S. Rahiminejad,E. Pucci, V. Vassilev, P-S.Kildal, S. Haasl, P. Enoksson, “Polymer Gapadapter for contactless, Robust, and fast Measurements at 220-325 GHz”,Journal of Microelectromechanical Systems, Vol. 25, No. 1, February2016, as also referred to above, which however is also not suitable fora V-band flange where the dimensions of pins and ridges are electricallylarger in terms of wavelength. The size of the flange is fixed andlimited, so there is basically no room to fit pins in the flange if acircular design for the ridge around the waveguide opening is adopted.

In FIG. 11 another embodiment of a central portion or structure 170Dwith a textured surface 15D comprising a number of protruding elements115D is disclosed. It has been realized that the long ridge or rim 151Dalso is important for stopping waves from propagating through the gap,and even makes it possible to reduce the number of rows of pins (or moregenerally protruding elements) needed for the design to even only one(see FIGS. 13A-13B). In the shown embodiment there are however two rowsof pins 115D. The rectangular rim or ridge 151D, 152D around thewaveguide 3D opening is modified in order to cover a larger frequencyband, for example in some implementations the whole frequency band from50 GHz to 75 GHz, although the invention of course not is limitedthereto, but it may be adapted to cover any appropriate or desiredfrequency band. Advantageously the rims or ridges 152D on the narrow orshort sides of the waveguide have a sufficient thickness to allow easymanufacture, for example between about 200-400μπι, preferably less than400 μm. The rims or ridges 151D along the wide or long sides of thewaveguide opening are divided into different sections, a central ridgesection, also denoted a platform 151D′, which has a thickness D2 ofabout λg/4, and outer narrower ridge sections 15ID″ with a thicknessD2′. Thus, the central ridge section or platform 151D′ does not have toextend all along the full length of the wide side of the waveguideopening.

The length L (FIG. 12) or extension of the central ridge section orplatform 151D′ can be optimized to give a good performance in terms ofleakage within the frequency band of interest, in some embodiments, forexample 50-75 GHz. It has also been realized that there is a relationbetween the thickness of the rim or ridge 152D along the narrow side ofthe waveguide opening and the length of the ridge or platform 151D′. Thelarger the thickness of the short side rim or ridge 152D, the shorterthe length L of the central ridge section, platform, 151D′.

For exemplifying reasons only, and by no means for limiting purposes,some exemplary dimensions are given for some different embodiments for a60 GHz flange adapter element. In one embodiment thick pins are usedhaving, for example, a diameter of about 670 μm, and a height of about1110 μm (full height). The wall thickness may, for example, be 200 μm inH-plane (thickness of walls of short ridge section 152D and outer ridgesections, 151D″), and λg/4 in E-plane, corresponding to the thickness ofthe wall of the central ridge section 151D′. The air gap may be about100 μm and the flange may have a total thickness of about 6.6 mm.

In one embodiment for a 60 GHz flange adapter element thin pins are usedhaving, for example, a diameter of about 400 μm. The wall thickness may,for example, be 200 μm in H-plane (thickness of walls of short ridgesection 152D and outer ridge sections, 151D″), and λg/4 in E-plane,corresponding to the thickness of the wall of the central ridge section151D′. The air gap may be about 100 μm and the flange may have a totalthickness of about 6.6 mm.

In still another embodiment for a 60 GHz flange adapter element thinpins are used having, for example, a diameter of about 400 μm and a wallthickness of about 300 μm in H-plane is used (thickness of walls ofshort ridge section 152D and outer ridge sections, 151D″), and λg/4 inE-plane, corresponding to the thickness of the wall of the central ridgesection 151D′. The air gap may be about 100 μm and the flange may have atotal thickness of about 6.8 mm.

FIG. 12 shows a central section or structure 170E with a texturedsurface and a waveguide surrounding rim or ridge structure as in FIG. 11in a back-to-back implementation, i.e. with the same periodic orquasi-periodic structures on both sides around the waveguide openings.Similar elements bear the same reference numerals as in FIG. 11 butindexed “E” and will therefore not be further discussed herein.

FIG. 13A shows another embodiment of a central portion or structure 170Fwith a textured surface 15F comprising a number of protruding elements115F. As discussed above with reference to FIG. 11, through therealization that the long ridge or rim 151F also is important forstopping waves from propagating through the gap, implementations withbut one row of protruding elements 115F on each side of the waveguideopening are advantageous, one example of which is shown in FIG. 13A. Therectangular rims or ridges 151F, 152F around the waveguide 3F openingare modified in order to cover a larger frequency band, for example, insome implementations the whole frequency band from 50 GHz to 75 GHz,although the invention of course not is limited thereto, but it may beadapted to cover any appropriate or desired frequency band.Advantageously the rims or ridges 152F on the narrow or short sides ofthe waveguide have a sufficient thickness to allow easy manufacture, forexample, between about 200-400 μm, preferably less than 400 μm. The rimsor ridges 151F along the wide or long sides of the waveguide opening aredivided into different sections, a central ridge section, also denoted aplatform, 151F′ which has a thickness of about λg/4, and outer narrowerridge sections 151F″. The central ridge section or platform 151F′ doesnot extend all along the full length of the wide side of the waveguide3F opening.

The length L (shown in FIG. 12) or extension of the central ridgesection or platform 151F′ can be optimized to have a good performance interms of leakage within the frequency band of interest, in someembodiments, for example, 50-75 GHz. As also referred to above, there isa relation between the thickness of the rim or ridge 152F along thenarrow side of the waveguide opening and the length of the ridge orplatform 151F′ provided on the wide side. The larger the thickness ofthe short side rim or ridge 152F, the shorter the length L (shown inFIG. 12) of the central ridge section, platform, 151F′ and vice versa.FIG. 13B is a top view of the central section 170F of FIG. 13A shownmerely for illustrative purposes.

FIG. 14A shows an embodiment of a flange adapter element comprising acentral section or structure 170F as in FIG. 13A, which therefore willnot be further discussed herein, and which is provided with an outerprotective or supporting section or element, for example a rim, 105F(see also reference numeral 105 in FIG. 1) which is disposed such as tosurround the periodic or quasiperiodic structure 15F, i.e. the texturedsurface. The shape of the outer protective or supporting section orelement, for example, a rim or similar, 105F is not important for theelectrical performance, but it is important to provide a support or acontact surface when two flanges are connected together, to protect theflange surfaces (smooth or textured) from damage. It also contributes inproviding a fixed gap between flanges, since the height of such an theouter protective or supporting section or element, rim, 105F is equal tothe height of the protruding elements 151F plus the gap for full-heightprotruding element structures, and the height of the protruding elementsplus half the gap for half-height protruding element structures, orcorrespondingly if different heights are used for the protrudingelements.

As for the embodiment described with reference to FIG. 1, the flangeadapter element 100F comprises wings or protruding sections in whichalignment pin holes 101F are provided, and between recesses, forexample, comprising U-shaped recesses 102F and waists 103F, are providedsuch as to leave space for fastening elements, for example, screws, withmagnetic heads or magnetic portions attached to the heads or similar asalso discussed earlier in the application, and therefore not will befurther described here.

FIG. 14B is a top view of the flange adapter element 100F of FIG. 14Ashown merely for illustrative purposes.

In FIG. 15A a set of alternative interconnecting elements 12G₁, 12G₂, isillustrated. Top and side views are shown in FIGS. 15B, 15C. The use ofsuch interconnecting elements, or fastening elements, is particularadvantageous in overcoming problems with flange adapter elements havingdifferent depths or thicknesses, and when magnetic elements should befastened to already existing or fabricated screws. The solution herecomprises the use of a fastening system comprising, here, four separateinterconnecting elements also serving as fasteners. They have a shapeadapted to the shape of a flange adapter element as described earlier inthe application; a particular implementation is shown in FIG. 16B.Elements not specific for this embodiment are not described in detailsince the have already been described with reference to precedingembodiments, and like elements are given the same reference numerals butreferenced “G”.

Here two different (and mirrored) shapes of interconnecting (orfastening) elements are used, first interconnecting elements 12G₁, alsocalled top/bottom fasteners, and second interconnecting elements 12G₂,also called side fasteners. Thereby the semantic look is increased andthe risk of incorrect mounting is reduced. Except for the outer shape,the design of the interconnecting elements 12G₁, 12G₂ is similar. In oneembodiment they have a shell-shaped configuration 122 adapted to theshape, for example, of a WR15-flange. Internally they are provided withdome-shaped protrusions 121 adapted to allow connection to existingscrew holes of the waveguide flange. On the front side cylindricalcasings 123 are provided for reception of permanent magnet elements 13G,for example, 3×2 mm neodymium magnets.

The interconnecting elements 12G₁, 12G₂, can easily be applied to awaveguide flange 10G, for example, a WR15-flange by snapping them intoplace towards the center of the flange 10G as shown in FIG. 16A. Thedome-shaped protrusions 121 and the radial shell shape 122 ensure thatthe interconnecting elements are fixed in place or position. Once theinterconnecting elements 12G₁, 12G₂, have been applied onto thewaveguide flange 10G, a flange gap adapter element 100G can be mountedusing alignment pins as described, for example, with reference to FIGS.3A, 3B. The shapes of the interconnecting elements and the alignmentpins ensure that the flange adapter element 100G will not be mountedincorrectly. By mounting four interconnecting elements or fasteners toan interconnecting waveguide flange (not shown) as shown in FIGS. 16A,and 16B the interconnection will be completed by aligning the waveguideflange onto the flange adapter element 100G, where it will be held inplace by means of magnetic elements as described earlier in theapplication. Preferably the interconnecting elements are attached to thewaveguide flange before the flange adapter element 100G in order toavoid damage to the flange adapter element, although it is not arequirement. For detachment of the interconnecting elements, they aresimply pulled from the center of the flange and drawn outwards. Inadvantageous embodiments the interconnecting elements 12G₁, 12G₂, aremade of plastic to provide for good elastic properties for mounting anddetachment purposes. In other embodiments they are made of metal.

The interconnecting elements 12G₁ and 12G₂ may then be attached by meansof screws from the backside of the waveguide flange.

The interconnecting elements may, for example, be fabricated by means ofjet molding or liquid injection molding. Of course also otherfabrication methods are possible as well.

It should be clear that the invention is not limited to the illustratedembodiments but that it can be varied in a large number of ways, andfeatures of the different embodiments can be freely combined.Particularly the periodic or quasi-periodic structures, textures, can beof many different kinds, i.e. the type, shape and size and arrangementof protruding elements, and the dimensions be scaled for differentfrequency bands, some figures are, for example, given for 60 GHzimplementations as far as dimensions of protruding elements, thicknessesof ridge sections around the waveguide opening etc. are concerned. Itshould also be clear that a flange adapter element can be implemented asa separate part allowing releasable connection to waveguide flanges,guided and slidable by means of alignment pins, or comprise a waveguideflange itself, or be adapted for fixed connection to a waveguide flange.Flange adapter elements may also be provided as back-to-back flangeadapter elements or single sided elements. Still further,interconnecting elements may comprise magnetic screw heads, or magnetsconnected to screw heads by means of gluing or similar, or magneticelements attached to other interconnecting elements, as well as magneticelements may be fastened on, or to, waveguide flanges or, particularlyfor flange adapter elements to be connected fixedly to a waveguideflange, or a flange support element (see for example, reference numeral145A in FIG. 5A) by gluing, for example, in small recesses or cavitiesor externally on the surface. Also the shapes and sizes of the wingsections, or the intermediate recesses admitting room forinterconnecting elements (for example, screws with magnetic elements),can be varied in different manners, only some exemplifying embodimentsbeing shown. It is also possible to use other fastening elements thanscrews with magnets, or magnets as such. Particular implementationsrefer to flange adapter elements with a surrounding protective orsupporting rim as such, independently of type of interconnectingelements.

In some embodiments the textured surface, i.e. the periodic orquasi-periodic structure, comprises a number of square shaped pins, withcross-sectional area dimension of (0.150λ)² and a height of 0.15λ-0.25λ,surrounding a waveguide opening. It may also comprise a corrugatedstructure with a plurality of concentrically or elliptically disposedcorrugations with grooves surrounding a waveguide opening.

As referred to above, the width, or cross-sectional dimension/the heightof the pins or corrugations of any appropriate kind is determined by thedesired frequency band. The higher the frequency band, the smaller thedimensions, and the dimensions scale linearly with the wavelength; thehigher the frequency, the smaller the wavelength, and the smaller thedimensions. For a frequency band, by wavelength is here meant thewavelength of the center frequency of the corresponding frequency band.

It is an advantage of the invention that, when magnetic interconnectingelements are used, a flange adapter element can be easily connected,loosened and reused in many different flange connections. It is also anadvantage, that when, for example, magnetic elements are used,connection and release is much faster than if other fastening mechanismsare used.

The concepts of the present invention are also applicable to circularwaveguides. The concepts are also applicable to waveguide flanges whichare not circular, but, for example, rectangular.

It particularly can be used for connecting a microwave or millimeterwave tool or instrument to a microwave or millimeter circuit or device,or a device under test (DUT) or a calibration arrangement for a tool orinstrument for analyzing or measuring microwave or millimeter circuitsor devices. With a microwave instrument is here also meant devices forfrequencies up to and above THz frequency.

It is an advantage that a waveguide interconnection arrangement isprovided which facilitates interconnection using existing standardwaveguide flanges.

The waveguide structure interconnecting arrangement further is compactand easy to assemble and reassemble—It is also a particular advantagethat the presence of a gap, enables relative displacement between thesurfaces, for example, two textured surfaces or a textured surface and asmooth surface, which is of advantage in some implementations, forexample, during calibration procedures etc. when a flange needs to bemoved.

It should be noted that the gap between surfaces is described as a gap,in some cases it may be substantially zero gap, the main point beingthat there is no requirement for any electrical contact between the twosurfaces.

1. An arrangement for interconnecting waveguide components, comprising:a waveguide flange adapter element having a first waveguide opening andbeing configured to provide an interconnection between first and secondwaveguide structures; a first waveguide flange of the first waveguidestructure having a second waveguide opening; the waveguide flangeadapter element comprising a first surface of a conductive material witha periodic or quasi-periodic structure formed by a number of protrudingelements surrounding the first waveguide opening; an interconnectorconfigured to releasably or fixedly interconnect the waveguide flangeadapter element to the first waveguide flange without requiringelectrical contact and to provide a first gap between a second surfacearound the first waveguide opening and the second waveguide opening andprovide a second gap between the first surface and a third surfacearound the second waveguide opening assuring that the first surface isnot in direct mechanical contact with the third surface of the waveguideflange, wherein the number of protruding elements surrounding the firstwaveguide opening allow waves to pass across the first gap in a desireddirection or waveguide path, at least in an intended frequency band ofoperation, and that stop propagation of waves in the first gap in otherdirections; wherein the second gap is smaller than λ/4, where λ is awavelength in a medium surrounding the protruding elements of awaveguide signal to be measured, the interconnector comprises a rim, aridge, a protective element or layer, or a supportive element or layerthat at least partly surrounds the periodically or quasi-periodicallyarranged protruding elements to provide the second gap; and wherein thewaveguide flange adapter element comprises alignment pin holessubstantially symmetrically disposed around, and at a distance from, thefirst surface, and the waveguide flange is aligned with respect to thefirst waveguide flange by alignment pins introduced into the alignmentpin holes and into cooperating pin holes in the first waveguide flangeto interconnect the waveguide flange to the first waveguide flange. 2.The arrangement of claim 1, further comprising a second waveguide flangeof the second waveguide structure or a second waveguide flange adapterelement connected to the waveguide flange adapter element, wherein thesecond waveguide flange or the second waveguide flange adapter elementis interconnected to the first waveguide flange.
 3. The arrangement ofclaim 1, wherein the interconnector further comprises interconnectingelements; the waveguide flange adapter element comprises a number ofthrough recesses, protruding sections, or wing portions for receiving atleast a portion of the interconnecting elements; the interconnectingelements comprise magnetic elements or magnetic portions adapted forcooperating with magnetic elements of the first waveguide flange, atleast some of the interconnecting elements include at least one ofsnap-on elements, clip-on elements, clamping elements, and fastenerswith magnetic heads or elements fixedly or releasably connected thereto.4. The arrangement of claim 3, wherein the waveguide flange adapterelement is interposed and aligned between the first waveguide flange ofthe first waveguide structure and a second waveguide flange of thesecond waveguide structure, and the first waveguide flange and thesecond waveguide flange are interconnected.
 5. The arrangement of claim1, wherein the interconnector further comprises interconnectingelements; the waveguide flange adapter element comprises a number ofthrough recesses, protruding sections, or wing portions for receivingthe interconnecting elements; the interconnecting elements comprisescrews; the waveguide flange adapter element has a thickness or heightthat corresponds to substantially twice a height of a of the respectivescrews or a protruding portion; and the screws are disposed in screwholes in both interconnecting waveguide flanges.
 6. The arrangement ofclaim 1, wherein the waveguide flange adapter element interconnects thefirst waveguide flange to a second waveguide flange of the secondwaveguide structure, the first waveguide flange has an associated smoothsurface; and the first surface faces the smooth surface of the firstwaveguide structure such that the gap less is than λ/4.
 7. Thearrangement of claim 6, wherein the waveguide flange adapter element isconnected to the smooth surface of the first waveguide flange byfasteners or glue.
 8. The arrangement of claim 1, wherein the firstwaveguide structure is interconnected to the second waveguide structureby the waveguide flange adapter, the first surface of the waveguideflange adapter element is optimized for low reflection coefficient andhigh transmission coefficient between the first and second waveguidestructures connected by the waveguide flange adapter element; the firstwaveguide flange has a smooth conductive surface, and a height of theprotruding element is between substantially λ/4-λ/2.
 9. The arrangementof claim 8, further comprising rim or ridge sections that surround thefirst surface of the waveguide flange adapter element.
 10. Thearrangement of claim 9, wherein a wall thickness of the rim or ridgesection is about λ_(g)/4, λ_(g) being a wavelength in the waveguide. 11.The arrangement of claim 1, wherein the number of protruding elements ofthe periodic or quasi-periodic structure are arranged in at least onerow around the first waveguide opening.
 12. The arrangement of claim 1,wherein the periodic or quasi-periodic structure provides a stopband forwaves leaking out from a gap between the first waveguide flanges and asecond waveguide flange of the second waveguide structure, such thatwaves passing from the second waveguide opening in the first waveguideflange to a third waveguide opening in the second waveguide flange areunaffected.
 13. The arrangement of claim 1, wherein the rim or ridgesections surround the first waveguide opening in the waveguide flangeadapter element, around which the periodic or quasi-periodic structureis disposed.
 14. The arrangement of claim 13, wherein the number ofprotruding elements of the periodic or quasi-periodic structure arearranged in between one and four rows around the first waveguideopening.
 15. The arrangement of claim 1, further comprising a secondwaveguide flange adapter element interconnected to the first waveguideflange adapter element, wherein a height of the protruding element isbetween λ/8-λ/4 for the waveguide flange adapter element interconnectedwith the second waveguide flange adapter element.
 16. An arrangement forinterconnecting waveguide components, comprising: first and secondwaveguide flange adapter elements, the first waveguide flange adapterelement comprising a first surface of a conductive material with aperiodic or quasi-periodic structure formed by a number of firstprotruding elements surrounding a first waveguide opening, the secondwaveguide flange adapter element comprising a second surface of aconductive material with a periodic or quasi-periodic structure formedby a number of second protruding elements surrounding a second waveguideopening; a first protruding element of the first protruding elementsfaces a second protruding element of the second protruding elements; thefacing first and second protruding elements each have a height or lengthsuch that a total height or length of the facing first and secondprotruding elements is a full length of the periodic or quasi-periodicstructure needed to stop propagation of waves inside a second gapbetween the two waveguide flange adapter elements in any direction andto allow waves to pass across a first gap from the first waveguideopening to the second waveguide opening in an intended frequency band;an interconnector configured for interconnecting the first and secondwaveguide flange adapters elements without requiring electrical contactand with assuring that the gap is present, hence assuring that the firstsurface is not in direct mechanical contact with the second surface;wherein the second gap is smaller than λ/4, where λ is a wavelength in amedium surrounding the protruding elements pins of a waveguide signal tobe measured, and wherein the interconnector comprises a rim, a ridge, aprotective element or layer, or a supportive element or layer that atleast partly surrounds surfaces formed by the periodically orquasi-periodically arranged protruding elements.
 17. The arrangement ofclaim 16, wherein each waveguide flange adapter element comprises fourprotruding sections or wing sections disposed around the correspondingfirst surface and a corresponding hole adapted for receiving acorresponding interconnecting element.
 18. The arrangement of claim 16,wherein the first waveguide flange adapter element is interconnected toa first waveguide flange of a first waveguide structure and the secondwaveguide flange adapter element is interconnected to a second waveguideflange of a second waveguide structure.
 19. The arrangement of claim 18,wherein the first waveguide flange has an associated smooth surface; andthe first surface faces the smooth surface of the first waveguidestructure and has a gap less is than λ/4.
 20. The arrangement of claim16, further comprising rim or ridge sections that surround the firstsurface of the first waveguide flange adapter element.